Retrospective evaluation of RET biomarker status and outcome to vandetanib in four phase III randomized NSCLC trials.

8045 Background: The prevalence of the tumorigenic KIF5B:RET fusion gene in NSCLC tumors has been estimated at 0.2–6% (Jiu et al 2012; Lipson et al 2012). We retrospectively analyzed tumor samples from 4 Phase III NSCLC trials of vandetanib, a TKI that selectively targets RET, VEGFR and EGFR signaling, to determine the prevalence of RET fusions and other RET biomarkers, and any potential association with outcome to vandetanib (V). Methods: The studies evaluated were ZODIAC (NCT00312377; docetaxel ± V 100mg), ZEAL (NCT00418886; pemetrexed ± V 100mg), ZEPHYR (NCT00404924; V 300mg vs placebo) and ZEST (NCT00364351; V 300mg vs erlotinib). RET biomarkers evaluated included RET fusions (including KIF5B:RET) and RET gene copy number (assessed by a 4-probe FISH assay), as well as RET protein expression (by IHC). Results: Of 4089 patients randomized across the 4 studies, 1291 and 1234 had tumor samples available for FISH and IHC analysis, respectively, with evaluable data obtained for 944 and 1102. RET fusions (in...